title: Characterization of a porcine model of post-operative pain.
abstract: BACKGROUND
  Management of acute pain related to surgical intervention, termed post-operative pain or POP, continues to be a major healthcare challenge. While the rat plantar incision model provides valuable data to researchers about the mechanisms mediating POP, the development of topical and localized treatments in small animal models is limited. To help address these issues, we describe here the characterization of a large animal model of incisional pain.
  
  
  METHODS
  Pigs underwent full-skin incision or full-skin and muscle incision and retraction (SMIR). Withdrawal thresholds were determined using the Von Frey test at baseline, 0.5-12 h post-surgery and on days 1, 2, 3, 5 and 7 post-surgery. The analgesic effects of systemic morphine [0.1 or 1.0 mg/kg intramuscular (i.m.) dose] and local anaesthetic ropivacaine were studied. Spontaneous pain-like behaviours were scored and analysed. The effects on wound healing were evaluated by gross observation and by histopathological examination.
  
  
  RESULTS
  Pigs incurring SMIR demonstrated significantly increased mechanical hypersensitivity compared with pigs that underwent full-skin incision only (p < 0.05). Maximal analgesia was achieved with morphine (1 mg/kg i.m. dose) at 0.5 h post-treatment. Local treatment with ropivacaine was effective at increasing the withdrawal threshold to Von Frey filaments compared with saline control (p < 0.05) for a period of at least 6 h. Wounds healed normally with no signs of infection, redness or swelling.
  
  
  CONCLUSIONS
  We propose that the pig model of incisional pain can provide an appropriate translational model for validating new topical and localized treatments for POP in humans.
authors.affiliation: The Neufeld Cardiac Research Institute and Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Castel
authors.forename: E
authors.initials: E
authors.lastname: Willentz
authors.forename: O
authors.initials: O
authors.lastname: Doron
authors.forename: O
authors.initials: O
authors.lastname: Brenner
authors.forename: S
authors.initials: S
authors.lastname: Meilin
mesh_terms: D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000818:Animals; D062109:Dermatologic Surgical Procedures / Q000379:methods; D004195:Disease Models, Animal; D009020:Morphine / Q000627:therapeutic use*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D010149:Postoperative Pain / Q000188:drug therapy*; D012867:Skin / Q000503:physiopathology; D013552:Swine
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine